title: Use of a catalytic model to estimate hepatitis A incidence in a low-endemicity country: implications for modeling immunization policies.
abstract: Evaluating the cost-effectiveness of vaccine programs with dynamic modeling requires accurate estimates of incidence over time. Because infectious diseases are often underreported, supplementary data and statistical analyses are required to estimate true incidence. This study estimates the true incidence of hepatitis A virus (HAV) infection in Canada using a catalytic model.
  
  
  
  A catalytic model was used to reconcile HAV seroprevalence data with the corresponding true cumulative risk of infection estimated from incidence data.
  
  
  
  The average annual reported incidence was 6.2 cases per 100,000 from 1980 to 1989 and 7.7/100,000 from 1990 to 1999, indicating that Canada is a low-incidence country. The seroprevalence in Canadian-born individuals (n = 7 studies) was approximately 1%-8% in ages <20, 1%-11% in ages 20-29, 7%-29% in ages 30-39, and higher in older age groups. Between 1980 and 1995, the catalytic model estimated an average annual incidence of 60/100,000 (95% confidence interval, 33-524); approximately 7.73 (4.21-67.33) times the average annual reported incidence of 7.78/100,000. For a typical birth cohort of 403 434 Canadians born in 1990, the model predicted 32 750 HAV cases by age 39, with a corresponding seroprevalence of approximately 8.12% by the year 2029.
  
  
  
  Reliable estimates of true incidence of infectious disease are required for cost-effectiveness analysis of infectious disease programs. Catalytic models enable the synthesis of dispersed data, quantification of data limitations, and reconciliation of these limitations to estimate true incidence for economic evaluations.
authors.affiliation: Toronto Health Economics and Technology Assessment Collaborative, University of Toronto, Toronto, Ontario, Canada (BP, MK)|Department of Health Policy, Management and Evaluation, University of Toronto (BP, MK)
authors.forename: Ba'
authors.initials: B
authors.lastname: Pham
authors.affiliation: Department of Biostatistics, University of Toronto (MHC)|Toronto General Hospital, University Health Network, Toronto (MHC)
authors.forename: Maggie Hong
authors.initials: MH
authors.lastname: Chen
authors.affiliation: Li Ka Shing Knowledge Institute of St Michael’s Hospital, Toronto (ACT)
authors.forename: Andrea C
authors.initials: AC
authors.lastname: Tricco
authors.affiliation: Leslie Dan Faculty of Pharmacy, University of Toronto (AA, MK)|GlaxoSmithKline Biologics, Rixensart, Belgium (AA)
authors.forename: Andrea
authors.initials: A
authors.lastname: Anonychuk
authors.affiliation: Toronto Health Economics and Technology Assessment Collaborative, University of Toronto, Toronto, Ontario, Canada (BP, MK)|Department of Health Policy, Management and Evaluation, University of Toronto (BP, MK)|Leslie Dan Faculty of Pharmacy, University of Toronto (AA, MK)|Department of Medicine, University of Toronto (MK)
authors.forename: Murray
authors.initials: M
authors.lastname: Krahn
authors.affiliation: Department of Mathematics and Statistics, University of Guelph, Guelph, Ontario, Canada (CTB)
authors.forename: Chris T
authors.initials: CT
authors.lastname: Bauch
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002170:Canada / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D016001:Confidence Intervals; D003661:Decision Support Techniques; D006291:Health Policy; D006506:Hepatitis A / Q000453:epidemiology* / Q000517:prevention & control*; D035922:Hepatitis A Antibodies / Q000302:isolation & purification; D006801:Humans; D015994:Incidence; D007223:Infant; D008875:Middle Aged; D015233:Models, Statistical; D008962:Models, Theoretical; D016036:Seroepidemiologic Studies; D055815:Young Adult
chemical_list: D035922:Hepatitis A Antibodies